Missing or incomplete firings in Otto engines lead to release of unburned or incompletely burned mixtures into the atmosphere or at least into any catalytic converter present. In addition to the impact on the environment, this leads to damage to the expensive and, in this respect, sensitive catalytic converter. Particularly in the case of Otto engines with many cylinders, e.g. six- to twelve-cylinder engines, the driver scarcely notices the loss of a single cylinder and, even in the case of misses or incomplete combustion in multiple cylinders, detects only a dropoff in power, which could be due to other causes. Thus, there is the danger that, in the event of such a defect in a many-cylindered Otto engine, the engine will continue to be driven, which leads to certain destruction of the catalytic converter.